Roofing materials having engineered coatings

ABSTRACT

An asphalt-based roofing material includes a coating having a top portion containing a mixture of asphalt and igneous and/or metamorphic rock particles, while the mat portion of the coating contains a mixture of asphalt and a filler which contains less than 10% igneous and/or metamorphic rock particles. In other embodiments, the top portion but not the bottom portion of the coating meets or exceeds a pliability standard, passes a weathering performance test, or has a high solar reflectance. In another embodiment relating to a laminated roofing material, the top portion but not the bottom portion has viscoelastic properties effective to prevent the coating from sticking to an adjacent shingle in a bundle. The invention also relates to a continuous process of applying first and second coatings to a mat for manufacturing a roofing material. In a first coating operation, a first asphalt-based coating is continuously applied to a first surface of the mat so that the first coating saturates the mat and forms a layer on the first surface. In a second coating operation, a second asphalt-based coating is continuously applied to a second surface of the mat so that the second coating forms a layer on the second surface. The second coating has different properties from the first coating.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 09/975,006 filed Oct. 10, 2001, now U.S. Pat. No. 7,238,408.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates generally to asphalt-based roofingmaterials, and more particularly to asphalt-based roofing materialshaving coatings which are engineered to vary in composition through thethickness of the roofing materials. The invention also relates toprocesses for coating the roofing materials.

BACKGROUND OF THE INVENTION

Asphalt-based roofing materials, such as roofing shingles, roll roofingand built-up roofing, are installed on the roofs of buildings to provideprotection from the elements. Typically, the roofing material isconstructed of materials including an inner mat such as a glass fibermat, an asphalt-based coating which saturates the mat and coats the topand bottom, and a layer of granules embedded in the top coating. Thecoating usually contains a filler such as ground limestone. Roofingshingles usually have a backdust material such as silica sand on thebottom coating to prevent them from sticking together in a bundle

The quantity and composition of the materials used to make a roofingmaterial determine, to a great extent, the performance of the resultantroofing material (e.g., weathering, cracking, blistering, algaeresistance, pliability, sticking, and impact resistance). They alsodetermine the cost to produce the roofing material. For a roofingshingle, the cost to produce the shingle is usually about 60-80%materials cost.

Current commercial roofing materials are typically produced with thesame asphalt and filler throughout (top coating, mat saturant coating,and bottom coating). Thus, each material in the coating must meet moreperformance criteria than if different materials could be used in thedifferent portions of the coating. This leads to compromises, typicallybetween cost and performance, but sometimes between one performanceparameter and another.

Some patents disclose roofing materials made with varied coatingcompositions. For example, U.S. Pat. No. 4,405,680 to Hansen discloses aroofing shingle including a mat saturated with a mixture of unblownasphalt and polymer, and coated with a mixture of a blown asphalt andfiller.

U.S. Pat. No. 4,848,057 to MacDonald et al. discloses a roofing shingleincluding a mat saturated with asphalt, coated with a rubber-modifiedasphalt on portions prone to cracking and a coating asphalt on otherportions, and further coated over all portions with the coating asphalt.

U.S. Pat. No. 5,488,807 to Terrenzio et al. discloses a roofing shingleincluding a mat saturated with asphalt, coated with a first coatingasphalt, and further coated with a second coating asphalt on portions ofthe shingle. The second coating asphalt has greater elongation orextensibility than the first, for example by modifying the asphalt witha polymer and a plasticizer.

U.S. Pat. No. 6,120,838 to Zickell discloses a roofing shingle includinga mat saturated and coated with a mixture of flux asphalt and recycledroofing material, and further coated with a polymer-modified asphalt.

In view of the current commercial roofing materials and those disclosedin the patents, there is still a need for roofing materials havingcoatings that are optimized as a whole for both performance and cost.There is also a need for a process for coating such roofing materials.

SUMMARY OF THE INVENTION

The above objects as well as others not specifically enumerated areachieved by an asphalt-based roofing material according to theinvention, and by a process according to the invention for coating theroofing material. In one embodiment, the roofing material comprises amat saturated and coated with an asphalt-based coating. The coatingincludes a top portion covering the top of the mat, a mat portionsaturating the mat, and a bottom portion covering the bottom of the mat.The top portion of the coating comprises a mixture of asphalt and rockparticles which are igneous rock particles, metamorphic rock particles,or a mixture thereof. The mat portion of the coating comprises a mixtureof asphalt and filler, the filler containing no more than about 10%igneous and/or metamorphic rock particles.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The top portion ofthe coating meets or exceeds a pliability standard described in CSAStandard A123.5-98. The bottom portion of the coating does not meet thepliability standard.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The top portion ofthe coating includes a top surface layer. At least the top surface layerof the top portion passes a weathering performance test as measured byat least 60 cycles-to-failure using ASTM Method D4799. The bottomportion of the coating does not pass the weathering performance test.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The top portion ofthe coating includes a top surface layer. At least the top surface layerof the top portion has a solar reflectance of at least 0.7 when testedby ASTM Method E903. The bottom portion of the coating has a solarreflectance less than 0.7.

In another embodiment, the roofing material is a laminated asphalt-basedroofing material. The laminated roofing material includes an underlaycomprising a mat saturated and coated with an asphalt-based coating. Thecoating includes a top portion covering the top of the mat, a matportion saturating the mat, and a bottom portion covering the bottom ofthe mat. The top portion of the coating includes a top surface layer.The laminated roofing material also includes an overlay coveting aportion of the top of the underlay, and leaving a portion of theunderlay uncovered. The overlay comprises a layer of an asphalt-basedcoating, the coating layer including a top surface layer. At is leastthe top surface layer of the overlay, and at least the top surface layerof the underlay on the uncovered portion of the underlay, are made withan asphalt having viscoelastic properties effective to prevent thecoating from sticking to a coating of an adjacent shingle when theshingles are stacked face to face in a bundle and stored at atemperature exceeding 90° F. (32° C.). The bottom portion of theunderlay coating is made with an asphalt not having the specialviscoelastic properties.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The top portion ofthe coating includes a top surface layer. A layer of granules isembedded in the top surface layer. At least the top surface layer of thetop portion has an increased adhesion defined by a granule loss of lessthan 0.8 grams when the roofing material is soaked in water for sevendays and then tested by ASTM Method D4977. The bottom portion of thecoating does not have the increased adhesion.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The bottom portionof the coating has an increased toughness compared to the top portion ofthe coating, such that the roofing material has an increased impactresistance of at least one UL 2218 class compared to the same roofingmaterial having a bottom portion of the coating with the same toughnessas the top portion.

In another embodiment, the roofing material comprises a mat saturatedand coated with an asphalt-based coating. The coating includes a topportion covering the top of the mat, a mat portion saturating the mat,and a bottom portion covering the bottom of the mat. The top portion ofthe coating includes a top surface layer. A layer of granules isembedded in the top surface layer. At least the top surface layer of thetop portion has an increased adhesion defined by a granule loss of lessthan 0.8 grams when the roofing material is soaked in water for sevendays and then tested by ASTM Method D4977. The roofing material furthercomprises a web fused to the bottom portion of the coating. The roofingmaterial has an increased impact resistance of at least one UL 2218class compared to the same roofing material without the web.

The process according to the invention for coating the roofing materialis a continuous process of applying first and second asphalt-basedcoatings to a mat. The process comprises continuously moving acontinuous mat along a path. The mat has a first surface and a secondsurface. In a first coating operation, a first asphalt-based coating iscontinuously applied to the first surface of the mat in a manner so thatthe first coating saturates the mat and forms a layer on the firstsurface. Then, in a second coating operation, a second asphalt-basedcoating is continuously applied to the second surface of the mat in amanner so that the second coating forms a layer on the second surface.The second coating has different properties from the first coating.

In another embodiment, the invention is a continuous process of applyingfirst and second asphalt-based coatings to a mat for manufacturing aroofing material. The process comprising continuously moving acontinuous mat along a path, the mat having a first surface and a secondsurface. In a first coating operation, a first asphalt-based coating iscontinuously applied to the first surface of the mat in a manner so thatthe first coating saturates the mat and forms a layer on the firstsurface. Then, in a second coating operation, a second asphalt-basedcoating is continuously applied to the second surface of the mat with anapplicator roll in a manner so that the second coating forms a layer onthe second surface. The second coating operation includes the step ofscraping the second coating from the surface of the applicator roll andsmoothly applying the scraped coating to the mat. The first and secondcoatings can either be the same type of coating, or they can havedifferent properties.

The invention also relates to a coating apparatus for applying first andsecond asphalt-based coatings to a mat for manufacturing a roofingmaterial. The apparatus includes a pair of squeeze rolls forcontinuously applying a first asphalt-based coating to a first surfaceof the mat in a manner so that the first coating saturates the mat andforms a layer on the first surface. The apparatus also includes anapplicator roll for continuously applying a second asphalt-based coatingto a second surface of the mat in a manner so that the second coatingforms a layer on the second surface. The apparatus further includes ametering device positioned adjacent the applicator roll with a gaptherebetween, the size of the gap determining the thickness of the layerof second coating. The apparatus also includes a scraping device forscraping the second coating from the surface of the applicator roll andsmoothly applying the scraped coating to the mat. The first and secondcoatings can either be the same type of coating, or they can havedifferent properties.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiments, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a roofing shingle having a coatingaccording to the invention.

FIG. 2 is a cross-section of another embodiment of a roofing shinglehaving a coating according to the invention.

FIG. 3 is a perspective view of a laminated roofing shingle having acoating according to the invention.

FIG. 4 is a cross-section of another embodiment of a roofing shinglehaving a coating according to the invention.

FIG. 5 is a schematic view of process for coating a roofing materialaccording to the invention.

FIG. 6 is a schematic view of another embodiment of a process forcoating a roofing material according to the invention.

FIG. 7 is a schematic view of another embodiment of a process forcoating a roofing material according to the invention.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

The asphalt-based roofing materials of the invention can be roofingshingles, roll roofing, built-up roofing, or other similar materials.Typically, the roofing materials are embodied as roofing shingles.

The roofing materials include an inner mat which is saturated and coatedwith an asphalt-based coating. The mat can be any type known for use inreinforcing asphalt-based roofing materials, such as a mat, web, scrimor felt of fibrous materials such as mineral fibers, cellulose fibers,rag fibers, synthetic fibers such as polymer fibers, or mixturesthereof. Preferably, the mat is a nonwoven mat of glass fibers.

Except as described below, the “asphalt” used in the asphalt-basedcoating can be any suitable type of bituminous material, such as anasphalt, tar or pitch The asphalt can be either a naturally occurringasphalt or a manufactured asphalt, such as an asphalt produced byrefining petroleum. The coating may also include other materials, suchas fillers, polymers, waxes, stabilizers, pigments, antioxidants, and/orsolvents. However, as described below, in certain embodiments of theinvention the type of asphalt in the coating, the other materials in thecoating, and/or the processing of the coating are specificallyengineered for different portions of the coating.

The roofing materials of the invention have coatings which vary incomposition through the thickness of the roofing materials. The conceptis to “tune” the performance of the coating by adjusting its compositionthrough the thickness. This can yield either better performance or lesscost with the same performance. The invention provides roofing materialsthat are optimized as a whole fox both performance and cost.

In one embodiment of the invention, the coating on the mat is varied incomposition to provide a roofing material that is resistant to algaegrowth and resistant to premature failure by cracking, while at the sametime being reduced in cost. As shown in FIG. 1, a roofing material 10according to the invention includes a mat 12 saturated and coated withan asphalt-based coating 14. The coating includes a top portion 14Acovering the top of the mat, a mat portion 14B saturating the mat, and abottom portion 14C covering the bottom of the mat. As used herein, “top”means the side facing upward or away from the roof when the roofingmaterial is installed on a roof, and “bottom” means the side facingdownward or toward the roof. The roofing material usually includes alayer of roofing granules 16 (not drawn to scale) embedded in the topportion of the coating.

The top portion 14A of the coating comprises a mixture of asphalt androck particles selected from the group consisting of igneous rockparticles, metamorphic rock particles, and mixtures thereof. When usedas a filler in the top coating, the igneous or metamorphic rockparticles provide a roofing material having resistance to algae growth.These types of rock particles do not support algae growth on thefinished roofing material. One reason may be that the igneous andmetamorphic rock particles are usually harder than other types of fillermaterials such as ground limestone. The igneous and metamorphic rockparticles are also very resistant to moisture absorption, therebyresisting algae growth. Many igneous and metamorphic rock particles arealso lower in cost than other filler materials.

Any type of igneous or metamorphic rock particles can be used that aresuitable as a filler in an asphalt-based top coating 14A. Somenonlimiting examples of suitable igneous rocks include trap rock,granite, basalt, obsidian, and pumice. Some nonlimiting examples ofsuitable metamorphic rocks include slate, quartz, amethyst, marble,gneiss, and graphite. Trap rock particles are a preferred type of rockparticle for use as a filler in the top coating. The rock particles areusually finely ground particles or powders. Typically, the filler isused in an amount of about 30-75% by total weight of the coating.

Although igneous and metamorphic rock particles provide resistance toalgae growth, they may cause premature failure (via cracking) of aroofing material when used as a fillet throughout the entire coating,presumably due to interaction with the mat. Consequently, the matportion 14B of the coating is made from a mixture of asphalt and afillet which contains less than about 10% igneous and/or metamorphicrock particles. Preferably, the filler is substantially flee of igneousand/or metamorphic rock particles. By using the igneous or metamorphicrock particles as a filler only in the top coating and not in the matcoating, the algae resistance characteristics can be obtained withoutthe increased risk of premature failure.

Any type of suitable filler besides igneous or metamorphic rockparticles can be used in the mat portion 14B of the coating. Preferably,the same filler is also used in the bottom portion 14C of the coating.Some nonlimiting examples of suitable fillers include particles ofsedimentary rocks or minerals such as limestone, dolomite, silica, talc,shale, clay, or mica. Other suitable fillers include fly ash, carbonblack, and inorganic fibers. Typically, the filler comprises sedimentaryrock particles. In a preferred embodiment of the invention, trap rockparticles are used as a filler in the top coating 14A and limestoneparticles are used as a fillet in the mat coating 14B and the bottomcoating 14C.

In another embodiment of the invention, the coating of the roofingmaterial is varied in composition to improve handling and avoid crackingwhile limiting the cost of the roofing material. Shingle handling(pliability, especially in cold conditions) has become more importantwith the increased popularity of premium and laminated shingles. Theformation of cracks in the top surface of a shingle is the primarysymptom of poor cold handling.

Referring again to FIG. 1, the handling of the roofing material 10 isimproved by using an asphalt-based coating having a high pliability orflexibility in the top portion 14A of the coating 14. The highpliability of the coating is defined by a pliability test described inCSA Standard A123.5-98, Section 8.5. In this Standard, five machinedirection and five cross-machine direction roofing material specimensare tested by bending them over the radius of a mandrel. The testconditions are the same as described in ASTM Method D228, except thatthe test temperature is 32° F.+/−5° F. (0° C.+/−3° C.) and the mandrelradius is 2 inches +/− 1/16 inch (5.1 cm+/−0.2 cm). A roofing materialhaving high pliability meets or exceeds the pliability requirements ofTable 1 in CSA A123.5-98.

One way to increase the pliability of the coating is to use an asphaltin the coating which was treated by ferric treatment during itsprocessing. The ferric treatment produces a softer asphalt. Thepliability of the asphalt may also be improved by modifying the asphaltwith a rubber material, such as an SBS rubber.

However, the highly pliable coating is usually more costly than atypical asphalt-based coating. Since the formation of cracks in the topsurface is the prime symptom of poor cold handling, the highly pliablecoating can be used only in the top portion 14A of the coating, not thebottom portion 14C. In some embodiments, the mat portion 14B of thecoating also does not have the high pliability.

It should be noted that fox purposes of testing the differentasphalt-based coatings for pliability according to CSA StandardA123.5-98, separate test roofing materials are produced with thedifferent coatings applied to coat the entire roofing material (topportion, mat portion and bottom portion). The same procedure is used forother tests described below.

In another embodiment of the invention, the coating of the roofingmaterial is varied in composition to provide excellent weatheringperformance while reducing the cost of the roofing material. Over time,the effects of weather on the coating of a roofing material may causedeterioration of the coating, such as brittleness and cracking.Therefore, it is desirable to provide a coating having the ability towithstand the effects of weather without deteriorating for a long periodof time. Weathering performance of coating asphalt is an importantselection criterion, eliminating many lower cost asphalts for use intypical footing materials.

FIG. 2 illustrates a rooting material 20 according to the inventionwhich has excellent weathering performance while being reduced in cost.The roofing material includes a mat 22 saturated and coated with anasphalt-based coating 24. The coating includes a top portion 24Acovering the top of the mat, a mat portion 24B saturating the mat, and abottom portion 24C covering the bottom of the mat The top portion 24A ofthe coating includes a top surface layer 24T. The roofing materialusually includes a layer of roofing granules 26 embedded in the topsurface layer 24T.

In accordance with the invention, at least the top surface layer 24T ofthe top portion 24A of the coating passes a weathering performance testas measured by at least 60 cycles-to-failure using ASTM Method D4799,“Standard Test Method for Accelerated Weathering Test Conditions andProcedures for Bituminous Materials (fluorescent UV and CondensationMethod)”, published March 2000 The top surface layer is preferably atleast about 0.023 inch (0.058 cm) thick. In one embodiment, the entiretop portion of the coating passes this weathering performance test.Using Cycle A of the test method, the coating material is exposed tocycles of four hours of UV light at 60° C., alternating with fours hoursof condensation at 50° C. The cycles are continued until the coatingmaterial fails due to cracking as determined by ASTM Test Method D1670.

However, the roofing material can be produced so that the bottom portion24C of the coating does not pass the weathering performance test. Thisallows the use of lower cost asphalts in the bottom portion. In someembodiments, the top portion 24A of the coating except for the topsurface layer 24T is also made with a lower cost asphalt, and/or the matportion 24B of the coating is also made with the lower cost asphalt.

An example of an asphalt which can be used to make a coating portionpassing the weathering test is an asphalt containing primarily AlaskaNorth Slope crude. An example of a lower cost asphalt which can be usedto make coating portions that do not pass the weathering test is anasphalt containing predominantly California crude.

In another embodiment of the invention, the coating of the rootingmaterial is varied in composition to increase the reflectivity or solarreflectance of the coating. A highly reflective coating would allow upto a 5% increase in shingle reflectivity in a standard shingle. A morereflective shingle can reduce the amount of solar radiation penetratingthe roof of a building, thereby lowering the air conditioning costs ofthe building. Alternatively, a highly reflective coating would allow theuse of less opaque (or fewer) granules. Referring again to FIG. 2, thereflectivity is increased by using an asphalt-based coating having ahigh reflectivity in at least the top surface layer 24T of the topportion 24A of the coating. The high reflectivity is defined by a solarreflectance of at least 0.7 when tested by ASTM Method E903. Anasphalt-based coating having a high reflectivity can be produced byincorporating metal flakes into the coating. These flakes may be furthercoated with metal oxides such as titanium dioxide or zinc sulfide tofurther increase the reflectivity.

However, the bottom portion 24C of the coating does not have the highreflectivity, because reflectivity is not needed in this portion of thecoating Specifically, the coating in this portion of the roofingmaterial has a solar reflectance less than 0.7. This allows the use oflower cost asphalts in the bottom portion. In some embodiments, the topportion 24A of the coating except for the top surface layer 24T is alsomade with a lower cost asphalt, and/or the mat portion 24B of thecoating is made with the lower cost asphalt.

In another embodiment of the invention, the roofing material is alaminated roofing material such as a laminated shingle. Laminatedroofing shingles are usually stacked face to face in a bundle. Theweight on the shingles in the bundle may cause the top coatings ofadjacent shingles to stick together, particularly in warm temperatures.In accordance with the invention, the coating of the roofing material isvaried in composition to reduce face to face sticking of shingles orother rooting materials when they are stacked together.

FIG. 3 illustrates a laminated roofing shingle 30 according to theinvention. The laminated shingle includes an underlay 32 and an overlay34 covering a portion of the top of the underlay, while leaving aportion of the underlay uncovered. Like the roofing material shown inFIG. 2, the underlay comprises a mat 22 saturated and coated with anasphalt-based coating 24. The coating includes a top portion 24Acovering the top of the mat, a mat portion 24B saturating the mat, and abottom portion 24C covering the bottom of the mat. The top portion 24Aof the coating includes a top surface layer 24T.

The overlay comprises a layer of an asphalt-based coating. Typically,like the roofing material shown in FIG. 2, the over lay furthercomprises a mat 22 which is saturated and coated with the layer ofasphalt-based coating 24. The coating includes a top portion 24Acovering the top of the mat, a mat portion 24B saturating the mat, and abottom portion 24C covering the bottom of the mat. The coating includesa top surface layer 24T. The laminated roofing material usually includesa top surface layer of roofing granules 36.

In accordance with the invention, at least the top surface layer of theoverlay, and at least the top surface layer of the underlay on theuncovered portion of the underlay, are made with an asphalt havingcertain viscoelastic properties. The viscoelastic properties prevent thecoating of one shingle from sticking to the coating of an adjacentshingle when the shingles are stacked face to face in bundles, thebundles are stacked onto pallets, and the pallets are stored attemperatures exceeding 90° F. (32° C.). In a specific embodiment, theshingles are Owens Corning Architectural Series laminated shingles, theshingles are stacked face to face in a bundle of 22 shingles, fourbundles ale stacked on top of one another on a pallet, and the pallet isstored at 95° F. (35° C.) for 24 hours. None of the coatings of theshingles stick together so as to cause damage to the shingles when theyare unpacked from the bundles. Preferably, the top surface layer of theoverlay, and the top surface layer of the underlay on the uncoveredportion of the underlay, are at least about 0.023 inch (0.58 cm) thick.In some embodiments, the entire top portion of the coating on theoverlay and on the uncovered portion of the underlay are made with anasphalt having the viscoelastic properties to prevent sticking.

However, asphalts having these viscoelastic properties can be high incost, and their use reduces the number of raw material choices.Consequently, instead of using such an asphalt for the entire roofingmaterial, a lower cost asphalt not having the viscoelastic propertiesbeing used for coating the bottom portion 24C of the coating. In someembodiments, the mat portion 24B is also made with the lower costasphalt.

An example of an asphalt having the viscoelastic properties is Trumbullasphalt manufactured by Owens Corning. An example of a lower costasphalt not having the viscoelastic properties is an asphalt containingpredominantly Venezuelan crude.

In another embodiment of the invention, the coating of the roofingmaterial is varied in composition to markedly improve resistance of theroofing material to hail damage. The impact of heavy hail on a roofingmaterial can cause granule loss, immediate or delayed, from the topsurface of the roofing material. In some instances, the impact of hailcan also cause a small tear or puncture in the roofing material.

Referring again to FIG. 2, resistance to granule loss caused by hailimpact is improved by using an asphalt-based coating having an increasedadhesion in at least the top surface layer 24T of the top portion 24A ofthe coating. In some embodiments the entire top portion 24A hasincreased adhesion. The increased adhesion is defined by a granule lossof less than 0.8 grams when the roofing material is soaked in water forseven days and then tested by ASTM Method D4977. The increased adhesioncan be obtained, for example, by modifying the asphalt with certainpolymers such as synthetic rubbers, e.g., SBS rubber.

However, since a coating having increased adhesion is usually morecostly than a typical coating, the cost is limited by using a coatingnot having the increased adhesion in the bottom portion 24C of thecoating. In some embodiments, the mat portion 24B also does not have theincreased adhesion.

As shown in FIG. 4, resistance to tear/puncture caused by hail impact isimproved by using an asphalt-based coating having increased toughness inthe bottom portion 44C of the coating 44. It has been found thatincreasing the toughness of the bottom portion of the coating by itselfis sufficient to reduce the occurrence of tears and punctures caused byhail impact. Consequently, the top portion 44A of the coating does notrequire the increased toughness. Specifically, the bottom portion of thecoating has an increased toughness compared to the top portion, suchthat the roofing material has an increased impact resistance of at leastone UL 2218 class compared to the same roofing material having a bottomportion of the coating with the same toughness as the top portion. Insome embodiments, the mat portion 44B also does not have the increasedtoughness.

The improved impact resistance of the roofing materials is demonstratedby the use of a standard method, UL 2218, “Standard for ImpactResistance of Prepared Roof Covering Materials”, UnderwritersLaboratories, May 31, 1996. In this method, the roofing material issecured to a test deck, and a steel ball is dropped vertically through atube onto the upper surface of the roofing material. The roofingmaterial can be tested at four different impact force levels: Class 1(the lowest impact force) through Class 4 (the highest impact force).The force of impact in the different classes is varied by changing thediameter and weight of the steel ball, and the distance the ball isdropped. For example, the Class 1 test uses a steel ball having adiameter of 1.25 inches (32 mm) weighing 0.28 pounds (127 g) that isdropped a distance of 12 feet (3.7 m), while the Class 4 test uses asteel ball having a diameter of 2 inches (51 mm) weighing 1.15 pounds(521 g) that is dropped a distance of 20 feet (6.1 meters). After theimpact, the roofing material is inverted and bent over a mandrel in boththe machine and cross directions, and the lower surface of the roofingmaterial is examined visually for any evidence of an opening or tear. A5× magnification device may be used to facilitate the examination of theroofing material. If no evidence of an opening is found, the roofingmaterial passes the impact resistance test at the UL 2218 class tested.Preferably, the roofing material has an increased impact resistance ofat least two UL 2218 classes. More preferably, the roofing materialmeets a UL 2218 Class 4 impact resistance standard.

The increased toughness of the bottom portion of the coating can beobtained, for example, by modifying the asphalt with certain polymers,such as synthetic rubber or ethylene vinyl acetate.

The bottom portion of the coating with increased toughness, and the topportion of the coating with increased adhesion, can be used together orseparately in a roofing material to provide their respective benefits.

In one embodiment of the invention, at least the top surface of the topportion of the coating has increased adhesion to prevent granule loss,as described above. For example, the top portion of the coating may bemade with a polymer-modified asphalt to increase its adhesion.Optionally, a layer of an adhesive material can be applied to the topsurface of the coating to further improve the granule adhesion. Thebottom portion of the coating does not have the increased adhesion. Aweb is fused to the bottom portion of the coating. The web improves theimpact resistance of the roofing material as described above. Theroofing material has an increased impact resistance of at least one UL2218 class compared to the same roofing material without the web.Suitable webs for improving the impact resistance of a roofing materialare described in U.S. Pat. No. 6,228,785, issued May 8, 2001, which isincorporated by reference in its entirety.

Some preferred embodiments of the asphalt-based roofing materials of theinvention are produced by a coating process that applies the top coatingindependently of the mat coating and the bottom coating, or that appliesthe bottom coating independently of the mat coating and the top coating(e.g., in the embodiment relating to a tougher bottom coating). FIGS.5-7 illustrate several different embodiments of preferred continuousprocesses according to the invention for coating roofing materials.

As shown in FIG. 5, a continuous mat 50 is moved continuously along apath, indicated by the arrows. The mat has a first surface 52 and asecond surface 54. In the illustrated embodiment, the first surface is abottom surface 52 of the mat, and the second surface is a top surface 54of the mat. As used herein, “top surface” and “bottom surface” refer tothe orientation of the mat surfaces in the roofing material which isprepared using the mat.

In the embodiment shown in FIG. 5, the mat 50 is inverted before thefirst coating operation so that the bottom surface 52 is oriented upwardwhen applying the first coating to the bottom surface. In theillustrated embodiment, the mat is inverted by passing the mat around afirst roll 56 and a second roll 58.

In a first coating operation, indicated generally at 60, a firstasphalt-based coating 62 is continuously applied to the bottom surface52 of the mat 50 in a manner so that the first coating saturates the matand forms a layer on the bottom surface. In the embodiment shown, thefirst coating operation comprises moving the mat through a gap 64between an upper squeeze roll 66 and a lower squeeze roll 68. The firstcoating 62 is supplied to a location before the gap and above the mat sothat the first coating moves through the gap with the mat. In theillustrated embodiment, the first coating is supplied by a trough 70 tothe nip 72 between the upper and lower squeeze rolls. However, it couldalso be supplied at a location before the nip. The first coating is fedto the applicator via a pipeline (not shown) from a first coating supplysource (not shown).

The squeeze rolls force the first coating to enter and saturate the matand to form a layer on the bottom surface 52 of the mat (which is noworiented upward). The size of the gap between the squeeze rolls controlsthe thickness of the layer of first coating on the bottom surface of themat. Preferably, the upper squeeze roll 66 rotates in a direction sothat the surface of the upper squeeze roll adjacent the mat moves in adirection opposite the direction of the mat. The opposite direction ofmovement of the upper squeeze roll promotes a smooth surface of thefirst coating. Preferably, the lower squeeze roll 68 rotates in adirection so that the surface of the lower squeeze roll adjacent the matmoves in the same direction as the mat.

In a second coating operation, indicated generally at 74, a secondasphalt-based coating 76 is continuously applied to the top surface 54of the mat 50 (now oriented downward) in a manner so that the secondcoating forms a layer on the top surface. In some preferred embodimentsof the invention, the second coating has different properties from thefirst coating. However, in other embodiments of the invention, thesecond coating can be the same type of coating as the first coating,having the same properties. In the embodiment shown, the second coatingis applied to the mat with a large applicator roll 78. Roll 79positioned beside the applicator roll forms the other surface of thereservoir for the coating 76. The second coating 76 is supplied to thereservoir by an applicator (not shown) and flows onto the applicatorroll 78 for application to the mat. In the illustrated embodiment, thesecond coating operation also employs a metering bar or roll 80positioned adjacent the applicator roll with a gap 82 therebetween Themetering roll wipes off all but the desired film thickness, set by thesize of the gap between the applicator roll and the metering roll.

The applicator roll usually rotates in a direction so that the surfaceof the applicator roll adjacent the mat moves in the same direction asthe mat, and the surface of the applicator roll moves at a speedpreferably relatively close to the sheet speed, preferably within arange of from about 90% to about 110% of the speed of the mat. Oneskilled in the art appreciates that the speed range may be adjusted toachieve proper coating of the mat. The metering roll rotates in adirection opposite the direction of the applicator roll so that thesecond coating is held in the reservoir. Preferably, the mat wraps onthe applicator roll to promote wetting and transfer of the secondcoating to the mat, more preferably over at least about 120 degrees ofthe roll (it wraps 180 degrees in the embodiment shown).

Preferably, the second coating operation employs a device 84 to scrapethe second coating from the surface of the applicator roll and smoothlyapply the coating to the mat. In the illustrated embodiment, the deviceis generally bar-shaped, and it is positioned in the nip (indicatedgenerally at 86) between the applicator roll and the mat. Such a devicecan help to ensure substantially 100% transfer of the coating from theroll to the mat.

Preferably, the first and second coating operations can be independentlycontrolled in a dial-in mode in which control parameters are set onceand do not require adjustment throughout the continuous process. Such aprocess is much more efficient than a process requiring feedback andadjustment of the controls.

After the first and second coatings have been applied to the mat, themat moves over a rounded exit support 88 for further process steps (notshown) in the manufacture of the roofing material, such as granuleapplication, cooling and cutting.

In the embodiment of the process shown in FIG. 6, the mat 50 is notinverted before the first coating operation. Consequently, the bottomsurface 52 of the mat is oriented downward when applying the firstcoating to the bottom surface. Like in the first embodiment, the processincludes a first coating operation, indicated generally at 90, in whichthe first coating is continuously applied to the bottom surface of themat in a manner so that the first coating saturates the mat and forms alayer on the bottom surface. In the embodiment shown, the first coatingoperation involves moving the mat through a gap 92 between an uppersqueeze roll 94 and a lower squeeze roll 96. The first coating 62 issupplied to a location before the gap and below the mat so that thefirst coating moves through the gap with the mat. The squeeze rollsforce the first coating to enter and saturate the mat and to form alayer on the bottom surface of the mat. The size of the gap between theupper squeeze roll and the lower squeeze roll controls the thickness ofthe layer of first coating.

Preferably, the lower squeeze roll 96 rotates in a direction so that thesurface of the lower squeeze roll adjacent the mat moves in a directionopposite the direction of movement of the mat. The opposite direction ofmovement of the lower squeeze roll promotes a smooth surface of thefirst coating. Preferably, the upper squeeze roll 94 rotates in adirection so that the surface of the upper squeeze roll adjacent the matmoves in the same direction as the mat.

The first coating can be supplied to the location before the gap andbelow the mat in any suitable manner. Preferably, the first coating issupplied by applying a layer of the first coating to the bottom surfaceof the mat before moving the mat through the squeeze rolls. In theembodiment shown in FIG. 6, the first coating is supplied by applyingthe layer of first coating to the bottom surface of the mat with aninking roll 98 which draws molten coating from a tub 97. The inking rollslathers on a layer of the first coating for use in the squeeze rolls. Ametering bar 99 defines a gap where coating is allowed to pass, therebycontrolling the amount of coating that goes onto the mat; the test ofthe coating falls back into the tub. The illustrated process does notuse a nip roll with the inking roll. The height of the inking roll, andthe resulting position of the mat, is controlled so that the mat doesnot wrap on the lower squeeze roll.

In the embodiment shown in FIG. 7, the first coating is supplied byfeeding the first coating to the nip 100 between the mat 50 and thelower squeeze roll 96. The first coating can be fed to the nip by anysuitable means. Preferably, it is fed to the nip via a trough (notshown) that seals against the lower squeeze roll. The trough may be keptoverflowing by filling on one side and flowing over a weir on the other.

Referring to FIGS. 6 and 7, in a second coating operation, indicatedgenerally at 102, a second asphalt-based coating 76 is continuouslyapplied to the top surface 54 of the mat 50 in a manner so that thesecond coating forms a layer on the top surface. The second coating hasdifferent properties from the first coating. In the embodiment shown,the second coating is applied to the mat with an applicator roll 104. Inthe illustrated embodiment, the second coating operation also employs ametering roll 106 positioned beside the applicator roll with a gap 108therebetween. The second coating 76 is supplied above the gap and flowsthrough the gap onto the applicator roll for application to the mat. Thesize of the gap between the applicator roll and the metering rollcontrols the thickness of the second coating on the mat. Preferably, adevice (not shown) to scrape the second coating from the surface of theapplicator roll and smoothly apply it to the mat is positioned in thenip between the applicator roll and the mat.

Preferably, the applicator roll rotates in a direction so that thesurface of the applicator roll adjacent the mat moves in the samedirection as the mat, and the surface of the applicator roll moves at aspeed within a range of from about 90% to about 110% of the speed of themat. The metering roll rotates in a counterclockwise direction so thatthe moving surface of the metering roll holds the second coating abovethe gap. Preferably, the mat at least slightly wraps on the applicatorroll to promote wetting and transfer of the second coating to the mat.In the illustrated embodiment, the mat moves over a rounded exit support88 which is positioned to cause a slight wrap of the mat on theapplicator roll. Preferably, the second coating operation employs adevice (not shown) to scrape the second coating from the surface of theapplicator roll and smoothly apply the coating to the mat.

In an alternate embodiment of the second coating operation (not shown),the applicator roll rotates in a direction so that the surface of theapplicator roll adjacent the mat moves in a reverse direction relativeto the mat movement. The metering roll is positioned on the other sideof the applicator roll, and it rotates in a clockwise direction. Ametering bar is positioned at a 10 o'clock position relative to theapplicator roll, controlling the thickness of the coating. No device isneeded to scrape the applicator roll, as the mat wipes all the coatingoff. Preferably, the speed of the applicator roll is about 30-50% of thespeed of the mat, in the reverse direction. One skilled in the artappreciates that the speed may be adjusted to vary the thickness, aslower speed will result in a thicker coating, and a faster speed willresult in a thinner coating, and increase the sheet tension.

The principle and mode of operation of this invention have beendescribed in its preferred embodiments. However, it should be noted thatthis invention may be practiced other wise than as specificallyillustrated and described without departing from its scope.

1. A continuous process of applying first and second asphalt-basedcoatings to a mat for manufacturing a roofing material, the processcomprising: continuously moving a continuous mat along a path, the mathaving a first surface and a second surface; in a first coatingoperation, continuously applying a first asphalt-based coating to thefirst surface of the mat in a manner so that the first coating saturatesthe mat and forms a layer on the first surface and does not form a layeron the second surface; and then in a second coating operation,continuously applying a second asphalt-based coating to the secondsurface of the mat in a manner so that the second coating forms a layeron the second surface and does not form a layer on the first surface;the second coating having properties which differ from the first coatingin at least one of the following aspects: (a) one of the first andsecond coatings meets or exceeds a pliability standard described in CSAStandard A123.5-98, and the other coating does not meet the pliabilitystandard; (b) one of the first and second coatings passes a weatheringperformance test as measured b at least 60 cycles-to-failure using ASTMMethod D4799, and the other coating does not pass the weatheringperformance test; (c) one of the first and second coatings has a solarreflectance of at least 0.7 when tested by ASTM Method E903, and theother coating has a solar reflectance of less than 0.7; (d) one of thefirst and second coatings has viscoelastic properties effective toprevent the coating from sticking to a coating of an adjacent roofingmaterial when the roofing materials are stacked face to face in a bundleand stored at a temperature exceeding 90° F. (32° C.), and the othercoating does not have the viscoelastic properties; (e) one of the firstand second coating has an increased adhesion defined by a granule lossof less than 0.8 grams when the roofing material is soaked in water forseven days and then tested by ASTM Method D4977, and the other coatingdoes not have the increased adhesion; (f) one of the first and secondcoatings includes a filler of igneous or metamorphic rock particles inan amount from about 30% to about 75% by weight of the coating, and theother coating includes from 0% to about 10% of the filler of igneous ormetamorphic rock particles; and (g) one of the first and second coatingshas an increased toughness compared to the other coating, such that theroofing material has an increased impact resistance of at least one UL2218 class compared to the same roofing material made without one of thecoatings having the increased toughness.
 2. A process according to claim1 wherein the first and second coating operations can be independentlycontrolled in a dial-in mode in which control parameters are set onceand do not require adjustment throughout the continuous process.
 3. Aprocess according to claim 1 wherein the first surface of the mat is abottom surface, and the first coating operation comprises applying thefirst coating to the bottom surface of the mat in a manner so that thefirst coating saturates the mat and forms a layer on the bottom surface.4. A process according to claim 3 wherein the mat is inverted before thefirst coating operation so that the bottom surface is oriented upwardwhen applying the first coating.
 5. A process according to claim 4wherein the first coating operation comprises moving the mat through agap between an upper squeeze roll and a lower squeeze roll, andsupplying the first coating to a location before the gap and above themat so that the first coating moves through the gap with the mat, thesqueeze rolls forcing the first coating to enter and saturate the matand to form a layer on the bottom surface of the mat.
 6. A processaccording to claim 5 wherein the upper squeeze roll rotates in adirection so that the surface of the upper squeeze roll adjacent the matmoves in a direction opposite the direction of the mat.
 7. A processaccording to claim 6 wherein the lower squeeze roll rotates in adirection so that the surface of the lower squeeze roll adjacent the matmoves in the same direction as the mat.
 8. A process according to claim6 wherein the size of the gap between the upper squeeze roll and thelower squeeze roll controls the thickness of the layer of first coatingon the mat.
 9. A process according to claim 3 wherein the bottom surfaceis oriented downward when applying the first coating to the bottomsurface.
 10. A process according to claim 9 wherein the first coatingoperation comprises moving the mat through a gap between an uppersqueeze roll and a lower squeeze roll, and supplying the first coatingto a location before the gap and below the mat so that the first coatingmoves through the gap with the mat, the squeeze rolls forcing the firstcoating to enter and saturate the mat and to form a layer on the bottomsurface of the mat.
 11. A process according to claim 10 wherein thelower squeeze roll rotates in a direction so that the surface of thelower squeeze roll adjacent the mat moves in a direction opposite thedirection of the mat.
 12. A process according to claim 11 wherein theposition of the mat is controlled so that the mat does not wrap on thelower squeeze roll.
 13. A process according to claim 11 wherein theupper squeeze roll rotates in a direction so that the surface of theupper squeeze roll adjacent the mat moves in the same direction as themat.
 14. A process according to claim 10 wherein the size of the gapbetween the upper squeeze roll and the lower squeeze roll controls thethickness of the layer of first coating on the mat.
 15. A processaccording to claim 10 wherein the first coating is supplied by applyinga layer of the first coating to the bottom surface of the mat beforemoving the mat though the squeeze rolls.
 16. A process according toclaim 15 wherein the first coating is supplied by applying the layer offirst coating to the bottom surface of the mat with an inking roll. 17.A process according to claim 10 wherein the first coating is supplied byfeeding the first coating to a nip between the mat and the lower squeezeroll.
 18. A process according to claim 17 wherein the first coating isfed to the nip via a trough which seals against the lower squeeze roll.19. A process according to claim 1 wherein the second coating is appliedwith an applicator roll, and including the step of scraping the secondcoating from the surface of the applicator roll and smoothly apply thescraped coating to the mat.
 20. A process according to claim 1 whereinthe second coating is applied with an applicator roll, and wherein thesecond coating operation further employs a metering roll positionedadjacent the applicator roll with a gap therebetween, the size of thegap controlling the thickness of the second coating on the mat.
 21. Aprocess according to claim 20 wherein the applicator roll rotates in adirection so that the surface of the applicator roll adjacent the matmoves in the same direction as the mat.
 22. A process according to claim21 wherein the surface of the applicator roll adjacent the mat moves ata speed within a range of from about 70% to about 130% of the speed ofthe mat.
 23. A process according to claim 21 wherein the surface of theapplicator roll adjacent the mat moves at a speed within a range of fromabout 90% to about 110% of the speed of the mat.
 24. A process accordingto claim 1 wherein the second coating is applied with an applicatorroll, and wherein the mat wraps on the applicator roll to promotewetting and transfer of the second coating to the mat.
 25. A processaccording to claim 24 wherein the mat wraps on the applicator roll overat least about 120 degrees of the applicator roll.
 26. A processaccording to claim 20 wherein the applicator roll rotates in a directionso that the surface of the applicator roll adjacent the mat moves in thea direction which is reverse the direction of the mat, and wherein thesurface of the applicator roll adjacent the mat moves at a speed withina range of from about 10% to about 100% of the speed of the mat.
 27. Aprocess according to claim 20 wherein the applicator roll rotates in adirection so that the surface of the applicator roll adjacent the matmoves in the a direction which is reverse the direction of the mat, andwherein the surface of the applicator roll adjacent the mat moves at aspeed within a range of from about 20% to about 60% of the speed of themat.
 28. A process according to claim 20 wherein the applicator rollrotates in a direction so that the surface of the applicator rolladjacent the mat moves in the a direction which is reverse the directionof the mat, and wherein the surface of the applicator roll adjacent themat moves at a speed within a range of from about 30% to about 50% ofthe speed of the mat.
 29. A process according to claim 3 wherein thesecond coating meets or exceeds the pliability standard and the firstcoating does not.
 30. A process according to claim 3 wherein the secondcoating passes the weathering performance test and the first coatingdoes not.
 31. A process according to claim 3 wherein the second coatinghas the solar reflectance of at least 0.7 and the first coating has asolar reflectance of less than 0.7.
 32. A process according to claim 3wherein the second coating has the viscoelastic properties and the firstcoating does not.
 33. A process according to claim 3 wherein the secondcoating has the increased adhesion and the first coating does not.
 34. Aprocess according to claim 3 wherein the second coating includes thefiller of igneous or metamorphic rock particles in an amount from about30% to about 75% by weight of the coating, and the first coatingincludes from 0% to about 10% of the filler of igneous or metamorphicrock particles.
 35. A process according to claim 1 wherein the firstsurface of the mat is a top surface, and the first coating operationcomprises applying the first coating to the top surface of the mat in amanner so that the first coating saturates the mat and forms a layer onthe top surface, and wherein the second coating has the increasedtoughness compared to the first coating.
 36. A continuous process ofapplying first and second asphalt-based coatings to a mat formanufacturing a roofing material, the process comprising: continuouslymoving a continuous mat along a path, the mat having a bottom surfaceand a top surface; in a first coating operation, continuously applying afirst asphalt-based coating to the bottom surface of the mat in a mannerso that the first coating saturates the mat and forms a layer on thebottom surface and does not form a layer on the top surface; and then ina second coating operation, continuously applying a second asphalt-basedcoating to the top surface of the mat in a manner so that the secondcoating forms a layer on the top surface and does not form a layer onthe bottom surface; wherein the first and second coating operations canbe independently controlled in a dial-in mode in which controlparameters are set once and do not require adjustment throughout thecontinuous process; the second coating having properties which differfrom the first coating in at least one of the following aspects: (a) oneof the first and second coatings meets or exceeds a pliability standarddescribed in CSA Standard A123.5-98, and the other coating does not meetthe pliability standard; (b) one of the first and second coatings passesa weathering performance test as measured by at least 60cycles-to-failure using ASTM Method D4799, and the other coating doesnot pass the weathering performance test; (c) one of the first andsecond coatings has a solar reflectance of at least 0.7 when tested byASTM Method E903, and the other coating has a solar reflectance of lessthan 0.7; (d) one of the first and second coatings has viscoelasticproperties effective to prevent the coating from sticking to a coatingof an adjacent roofing material when the roofing materials are stackedface to face in a bundle and stored at a temperature exceeding 90° F.(32° C.), and the other coating does not have the viscoelasticproperties; (e) one of the first and second coatings has an increasedadhesion defined by a granule loss of less than 0.8 grams when theroofing material is soaked in water for seven days and then tested byASTM Method D4977, and the other coating does not have the increasedadhesion; (f) one of the first and second coatings includes a filler ofigneous or metamorphic rock particles in an amount from about 30% toabout 75% by weight of the coating, and the other coating includes from0% to about 10% of the filler of igneous or metamorphic rock particles;and (g) one of the first and second coatings has an increased toughnesscompared to the other coating, such that the roofing material has anincreased impact resistance of at least one UL 2218 class compared tothe same roofing material made without one of the coatings having theincreased toughness.
 37. A continuous process of applying first andsecond asphalt-based coatings to a mat for manufacturing a roofingmaterial, the process comprising: continuously moving a continuous matalong a path, the mat having a bottom surface and a top surface;inverting the mat before a first coating operation so that the bottomsurface is oriented upward when applying a first asphalt-based coatingto the bottom surface; in the first coating operation, continuouslyapplying the first coating to the bottom surface of the mat in a mannerso that the first coating saturates the mat and forms a layer on thebottom surface and does not form a layer on the top surface, wherein thefirst coating operation comprises moving the mat through a gap betweenan upper squeeze roll and a lower squeeze roll, and supplying the firstcoating to a location before the gap and above the mat so that the firstcoating moves through the gap with the mat, the squeeze rolls forcingthe first coating to enter and saturate the mat and to form the layer onthe bottom surface; and then in a second coating operation, continuouslyapplying a second asphalt-based coating to the top surface of the mat ina manner so that the second coating forms a layer on the top surface anddoes not form a layer on the bottom surface, wherein the second coatingis applied with an applicator roll, and including the step of scrapingthe second coating from the surface of the applicator roll and smoothlyapplying the scraped coating to the mat; the second coating havingproperties which differ from the first coating in at least one of thefollowing aspects: (a) one of the first and second coatings meets orexceeds a pliability standard described in CSA Standard A123.5-98, andthe other coating does not meet the pliability standard; (b) one of thefirst and second coatings passes a weathering performance test asmeasured by at least 60 cycles-to-failure using ASTM Method D4799, andthe other coating does not pass the weathering performance test; (c) oneof the first and second coatings has a solar reflectance of at least 0.7when tested by ASTM Method E903, and the other coating has a solarreflectance of less than 0.7; (d) one of the first and second coatingshas viscoelastic properties effective to prevent the coating fromsticking to a coating of an adjacent roofing material when the roofingmaterials are stacked face to face in a bundle and stored at atemperature exceeding 90° F. (32° C.), and the other coating does nothave the viscoelastic properties; (e) one of the first and secondcoatings has an increased adhesion defined by a granule loss of lessthan 0.8 grams when the roofing material is soaked in water for sevendays and then tested by ASTM Method D4977, and the other coating doesnot have the increased adhesion; (f) one of the first and secondcoatings includes a filler of igneous or metamorphic rock particles inan amount from about 30% to about 75% by weight of the coating, and theother coating includes from 0% to about 10% of the filler of igneous ormetamorphic rock particles; and (g) one of the first and second coatingshas an increased toughness compared to the other coating, such that theroofing material has an increased impact resistance of at least one UL2218 class compared to the same roofing material made without one of thecoatings having the increased toughness.
 38. A continuous process ofapplying first and second asphalt-based coatings to a mat formanufacturing a roofing material, the process comprising: continuouslymoving a continuous mat along a path, the mat having a first surface anda second surface; in a first coating operation, continuously applying afirst asphalt-based coating to the first surface of the mat in a mannerso that the first coating saturates the mat and forms a layer on thefirst surface and does not form a layer on the second surface; and thenin a second coating operation, continuously applying a secondasphalt-based coating to the second surface of the mat with anapplicator roll in a manner so that the second coating forms a layer onthe second surface and does not form a layer on the first surface, andincluding the step of scraping the second coating from the surface ofthe applicator roll and smoothly applying the scraped coating to themat.